JPS5913632A - Manufacture of beta-manganese dioxide - Google Patents

Abstract

PURPOSE:To manufacture beta-MnO2 which provides characteristics for showing stable discharge voltage over a long time to an Li-Mn cell, by dispersing gamma- MnO2 in an acidic soln. contg. Mg<2+> at a specified concn. as well as Mn<2+> and by heating the resulting slurry. CONSTITUTION:gamma-MnO2 is dispersed in an acidic soln. contg. Mn<2+>, and the resulting slurry is heated to manufacture beta-MnO2. At this time, 20-55g/l Mg<2+> is added to said soln. By this method, beta-MnO2 having superior characteristics as the material of the positive electrode of an Li-Mn cell can be manufactured.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing β-manganese dioxide from r-manganese dioxide.

Conventionally, as a method for producing β-manganese dioxide from r-manganese dioxide, β-manganese dioxide was heated in air at 350°C.
A method of heating at ~450C to effect r→β transition is known. However, the β-manganese dioxide produced by this method is
Even if Mnf (-Mnf) was used as the positive electrode active material in the pond, it was not possible to obtain a stable discharge pressure for a long period of time due to the remaining bound water.

In addition, as another production method (r↓, a method is known in which rmanganese dioxide is slurried in an acidic solution containing divalent manganese ions and heated.This method further includes a static method and a dynamic method. There are two methods.

The static method is a method in which the slurry is heated while being left still, and the dynamic method is a method in which the slurry is heated while being stirred by an impeller.

However, in the static method, the transition phenomenon is slow when the manganese ions are dilute, and when the manganese ions are concentrated, the product becomes lumps or forms a solid layer in the container and is difficult to wash. or it becomes difficult to remove. On the other hand, the dynamic method produces a slurry-like product, which causes problems in filling properties when molding the Canabari mixture. The method of the present invention was made to improve such drawbacks, and the method of the present invention involves adding rZ to an acidic solution containing divalent or trivalent manganese ions.
A method for making β-manganese dioxide is characterized in that in the method of crushing β-manganese dioxide in which manganese oxide is made into a slurry and heated, magne/lamb ions are allowed to coexist in the acidic solution.

Manganese ions (5 to 40 f/l) 1
r↓Hama et al.

Acid 1
q/l is usually used.

The concentration of magnesium ions is 20 to 559/l.

Preferably 30 to 409/l. 20y/
Below, the β-transition phenomenon is slow, and above 559/, magnenosulfate J crystallizes. 4. .

Tlj gauze of dodic acid n = mankan can be used as it is as an acidic solution containing divalent manganese in which magneurium and ions coexist.

"'1+" The effect of magnesium ions is influenced by the lateral change of divalent manganese ions and is particularly effective when the manganese ion concentration IW is low.

Example Using sulfuric acid, magnesium sulfate, r mankan dioxide, concentrated sulfuric acid 1N 110&/V, magnonium ion aW35y/
A @ solution with a divalent manganese ion concentration of 52/l is prepared. Add 300 g of the solution to 300 g of powdered γ manganese dioxide.
1 was made into a slurry and crystallization was continued at 90°C.

At 120 ■■, a black product with good sedimentation properties without lumps or sticking to the container was obtained.

The product was filtered by decantation using 300C11S (black water) five times, and the cake was dried at 107°C for 2 hours. The effects of various factors such as a degree, magnesium ions, and stirring on the time required for γ→β transition, the properties of the produced β manganese dioxide, and the heptachronicity are shown in one place.

Application example 1゜The first figure shows the fruits of the present invention! The β-manganese dioxide produced in Example ① was used as the positive electrode active material, and the conductor was mixed and molded with carbon powder and Def1con powder as a binder, and the electrolyte was mixed with a mixed solvent of propylene carbonate and 162 dimethoxy7 ethane. A lithium manganese battery was prepared by dissolving lithium chlorate at a concentration of l mo I / /l'/). It exhibits stable release and pressure over time, and has excellent properties not seen in β-manganese dioxide (B) obtained by the conventional heating method.

[Brief explanation of drawings]

Figure 1 shows a lithium-manganese battery using β-manganese dioxide obtained in Example 1 of the present invention as a positive electrode active material, and β-manganese dioxide heat-treated at 1100°C, which is conventionally used in lithium-manganese batteries. This is a comparison of the discharge curve of a lithium manganese battery.

Claims (1)

[Claims] A method for producing β-manganese dioxide in which β-manganese dioxide is slurried in an acidic solution containing divalent manganese ions and heated, characterized in that 20 to 55 y/l of magnesium ions are allowed to coexist in the acidic solution. β
Method for producing manganese dioxide.